1. Field of the Invention
The present invention relates to an apparatus for dispensing a liquid, for instance gasoline and the like liquid fuel to vehicles, and more particularly to such apparatus of the type wherein so-called "full tank dispensation" can automatically be accomplished.
2. Description of the Prior Art
The fuel dispensing services in commercial gasoline stations are generally classified into so-called "amount designated dispensation" wherein an operator dispenses fuel in an amount requested by a customer and so-called "full tank dispensation" wherein the operator dispenses the fuel until a fuel tank in the customer's vehicle is filled with the fuel. The full tank dispensation system is troublesome for the operator, since he must manually control a lever of the dispensing nozzle to dispense the fuel in the vehicle fuel tank which already contains an unknown amount of fuel and fill that fuel tank with the dispensed fuel while under his visual control. Manual operation under such visual control has a problem in that it is not always possible to avoid a possible overflow due to excess dispensation.
In order to solve the problem, there has been proposed an automatic dispensing nozzle with a fuel level sensor at the tip which detects the fuel and issues a signal to automatically stop flow of the fuel from the nozzle (for instance, U.S. Pat. No. 3,085,600, BP No. 955 163). In theory, such device is arranged so that the level sensor contacts the actual surface of the fuel in a vehicle fuel tank to issue the fuel detection signal and stop the fuel dispensing operation. Depending on the sectional configuration of the inlet part of the fuel tank, the level sensor contacts the splash of the fuel on the rebound of the fuel discharged from the dispensing nozzle into the fuel tank or a fuel bubble which is formed by the fuel discharge and which rises up prior to the actual fuel level in the fuel tank to issue the fuel detection signal. As a result, the fuel dispensing operation stops prior to the time that the fuel tank has completely been filled with the fuel.
For filling the fuel tank with fuel with use of such a prior art device, therefore, the operator must manually reopen a valve to recommence the fuel dispensation. In this case, it is necessary for the operator to squeeze the valve in order to avoid a too-early issuance of the fuel detection signal by the level sensor due to the splash or bubble of fuel. However, such valve operation requires a some skill. In other words, non-skilled operators may recommence the fuel dispensing operation at a large discharging rate and as a result, he must repeat the fuel dispense recommencing opertion, until the fuel tank is completely filled with the fuel. This reduces the working efficiency.